Chelsea's owner Roman Abramovich with the club's then chief executive Peter Kenyon in 2004. Kenyon left the club in 2010. Photograph: Peter Macdiarmid/Reuters

Chelsea Football Club appear to be involved in the funding of "third-party ownership" of players outside the Premier League, contrary to the Premier League's and Uefa's strong official condemnation of the practice. Company documents in the UK, Jersey and Ireland strongly suggest that Chelsea are working in partnership with José Mourinho's Portuguese agent Jorge Mendes, and the US company Creative Arts Agency, who buy "economic rights participation agreements" in footballers playing for other clubs outside the Premier League.

Roman Abramovich's Chelsea appear to be partners in the Quality Sports Investments and Quality Football Ireland network of companies, which operate via a complicated series of companies and several different funds in the tax haven of Jersey, to buy a percentage of players' "economic rights". The QSI funds seek to cash in by making a profit when the players are sold, operating via companies in Ireland, where corporation tax is set at 12.5%.

Asked by the Guardian to confirm or deny their involvement, and to explain the purpose of the Jersey investment entity the club unquestionably owns and discuss any possible conflicts of interest, Chelsea declined to discuss any aspect of it. However, Chelsea sources indicated the club considers it is not breaching any rules.

Chelsea's most recent annual accounts for 2012–13 state that the club, via one of its UK companies, Briskspring Ltd, owns a partnership registered in Jersey, Burnaby Investments LP. Until November 2012, this partnership was called Quality Sports III Investments LP. The Chelsea accounts say that the club's partner in Burnaby Investments LP is Burnaby GP Limited. Its country of registration is not specified, but there is no Burnaby GP in the UK or in Ireland. However, there is a Burnaby GP Limited registered in Jersey. Its most recent annual return, January 2013, discloses that it is jointly owned, 100 shares each, by CAA and Mendes's company, Gestifute International, which is registered in Ireland.

So, Chelsea appear to have formed a partnership with CAA and Mendes, and formed Burnaby Investments LP in Jersey, which the Chelsea accounts describe as an "investment company". The accounts do not explain the kind of investment that Burnaby Investments LP in Jersey conducts, and the club declined to explain. However, company records suggest it is linked to a company buying and selling footballers' "economic rights": Burnaby Investments Ireland Ltd. Until its name was changed in November 2012, that company was called Quality Football Ireland III Ltd.

This latter company, Burnaby Investments Ireland, stated in its financial accounts for the year to 31 December 2011 that "QSI III" had paid it a total of €10.5m. Of this money, Burnaby Investments Ireland spent €9.8m buying four "ERPAs," which are explained as players' "economic rights participation agreements", with two clubs. The accounts, stating that the money came from "QSI III", cover a period when Chelsea's partnership, Burnaby Investments LP in Jersey, was still called Quality Sports III Investments.

Burnaby Investments Ireland Ltd's financial accounts for the following year, to 31 December 2012, covering the period after Chelsea's Quality Sports III Investments LP had changed its name to Burnaby Investments LP, state that the €10.5m had been received from "the LP".

Photograph: Guardian

The shareholding of Burnaby Investments Ireland is held on trust "for charitable purposes" according to its accounts. Its directors are the Dublin-based accountants Rory Williams and Wendy Merrigan, who declined to answer any questions, including whether Chelsea are involved. The Quality Sports Investment and Quality Football Ireland network operates through at least 10 separate entities in Jersey: five general partnerships, GPs, and five limited partnerships, LPs. According to sources involved, QSI operates different funds, raising money separately for them. CAA, an agency which from its Los Angeles headquarters predominantly represents Hollywood actors and rock bands, is understood to have ventured into the lucrative world of football in 2010-11, and is involved with three players' "economic rights participation" funds.

One of the companies, Quality Football Ireland Ltd, is 70% owned by CAA itself, with the other 30% equally owned by senior CAA directors Michael Levine, based in New York, and David O'Connor, in Los Angeles. The most recent accounts for this Irish company show that at 31 December 2012 it had £15m worth of "economic rights participation agreements", and that money moved between companies described as "QSI" and "QSI II". CAA declined to comment on their involvement with QSI or to confirm whether Chelsea had any involvement, but the agency is understood to be now seeking to sell its interests in this "economic rights" business.

The QSI, Burnaby Investments Ireland and Quality Football Ireland operation does not publicly disclose which players' economic rights it has bought, nor the clubs they are playing for. However, the Portuguese club Sporting Lisbon does declare which of its players are owned by "third-party" funds. Sporting's most recent annual report, for the year to 30 June 2013, lists nine players whose economic rights were sold – in percentages ranging from 25% to 50% – to Quality Football Ireland Limited, Quality Football Ireland III (now renamed Burnaby Investments Ireland) Limited and Quality Football Fund Ireland Limited (which no longer exists in that name).

These players included Ricky van Wolfswinkel, the Dutch striker now playing for Norwich City in the Premier League, after Sporting sold him last summer for £8.5m. The Sporting report shows that 50% of Van Wolfswinkel's economic rights were owned by the Quality Football Ireland companies – not specifying which one – which bought the 50% share for €2.5m. The Premier League has banned third-party ownership, which means Norwich's £8.5m payment had to buy out both Sporting's and Quality Football Ireland's half shares of Van Wolfswinkel.

A Norwich City spokesman said: "We can confirm we were aware of third-party ownership of Ricky van Wolfswinkel … Accordingly we liaised with the Football Association to ensure that all third-party ownership issues were properly resolved prior to the player's transfer."

It is not possible to see from the publicly filed company documents whether Chelsea's money, or Burnaby Investments LP, its wholly owned Jersey partnership apparently with Mendes and CAA, directly funded purchasing the economic rights in these Sporting Lisbon players. Even if Chelsea did, and are indeed involved in buying and selling "economic rights participation agreements" of players at other clubs, they seem not to be breaking Premier League rules because none of their players are third-party owned.

The Premier League banned "third-party ownership" of players at its clubs after the outcry over West Ham United's signing of Carlos Tevez and Javier Mascherano in 2006 while the Argentinian stars' economic rights were still owned by two tax haven-registered companies. Richard Scudamore, the Premier League's chief executive, for whom the Tevez affair lengthened into a rocky saga of lawsuits and disciplinary proceedings – West Ham were fined £5.5m for failing to disclose all the contracts – is wholly opposed to third-party ownership. Uefa strongly agrees, and has, in alliance with Scudamore, lobbied Fifa to ban the practice.

It is unclear if the Premier League ever considered the possibility that, despite having outlawed "third-party ownership" of players in English football, its clubs could be involved in third-party ownership of players in other leagues abroad. The Premier League declined to comment on Chelsea's apparent involvement.

That Chelsea should be in partnership with Mendes and CAA in the Burnaby venture, without openly discussing it, raises many questions. One inference is that Chelsea could be seeking through this involvement to secure options over players at other clubs.

Mendes and Kenyon worked closely together when, as the chief executive of United, Kenyon signed Mendes's clients Cristiano Ronaldo, Anderson and Nani. After he moved to Chelsea to spearhead Abramovich's multimillion pound desire for football trophies, Kenyon signed Mendes's players Deco, Ricardo Carvalho and Paulo Ferreira. Mendes's Gestifute company itself is known to buy players' economic rights as well as representing players, which means it receives a portion of the transfer fee when such a player is bought by another club.

The Guardian asked detailed questions about QSI, the Jersey and Irish companies and the apparent Chelsea involvement, of Mendes's company Gestifute and Kenyon. Like Chelsea, CAA and Williams, they declined to comment.